Charles Wheatstone

Sir Charles Wheatstone /ˈwiːtstən/[1] FRS HFRSE DCL LLD (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three-dimensional images), and the Playfair cipher (an encryption technique). However, Wheatstone is best known for his contributions in the development of the Wheatstone bridge, originally invented by Samuel Hunter Christie, which is used to measure an unknown electrical resistance, and as a major figure in the development of telegraphy.

Sir Charles Wheatstone
Wheatstone Charles drawing 1868
Wheatstone,
drawn by Samuel Laurence in 1868
Born6 February 1802
Died19 October 1875 (aged 73)
Paris, France
ResidenceUnited Kingdom
Known forWheatstone bridge, Playfair cipher, early contributions to Spectroscopy and Telegraphy
AwardsRoyal Medal (1840, 1843)
Albert Medal (1867)
Copley Medal (1868)
Scientific career
FieldsPhysics
InstitutionsKing’s College London

Life

Charles Wheatstone was born in Barnwood, Gloucestershire. His father, W. Wheatsone, was a music-seller in the town, who moved to 128 Pall Mall, London, four years later, becoming a teacher of the flute. Charles, the second son, went to a village school, near Gloucester, and afterwards to several institutions in London. One of them was in Kennington, and kept by a Mrs. Castlemaine, who was astonished at his rapid progress. From another he ran away, but was captured at Windsor, not far from the theatre of his practical telegraph. As a boy he was very shy and sensitive, liking well to retire into an attic, without any other company than his own thoughts.

Wheatstone English Concertina
Wheatstone English concertina

When he was about fourteen years old he was apprenticed to his uncle and namesake, a maker and seller of musical instruments at 436 Strand, London; but he showed little taste for handicraft or business, and loved better to study books. His father encouraged him in this, and finally took him out of the uncle's charge.

At the age of fifteen, Wheatstone translated French poetry, and wrote two songs, one of which was given to his uncle, who published it without knowing it as his nephew's composition. Some lines of his on the lyre became the motto of an engraving by Bartolozzi. He often visited an old book-stall in the vicinity of Pall Mall, which was then a dilapidated and unpaved thoroughfare. Most of his pocket-money was spent in purchasing the books which had taken his fancy, whether fairy tales, history, or science. One day, to the surprise of the bookseller, he coveted a volume on the discoveries of Volta in electricity, but not having the price, he saved his pennies and secured the volume. It was written in French, and so he was obliged to save again, until he could buy a dictionary. Then he began to read the volume, and, with the help of his elder brother, William, to repeat the experiments described in it, with a home-made battery, in the scullery behind his father's house. In constructing the battery, the boy philosophers ran short of money to procure the requisite copper-plates. They had only a few copper coins left. A happy thought occurred to Charles, who was the leading spirit in these researches, 'We must use the pennies themselves,' said he, and the battery was soon complete.

At Christchurch, Marylebone, on 12 February 1847, Wheatstone was married to Emma West. She was the daughter of a Taunton tradesman, and of handsome appearance. She died in 1866, leaving a family of five young children to his care. His domestic life was quiet and uneventful.

Though silent and reserved in public, Wheatstone was a clear and voluble talker in private, if taken on his favourite studies, and his small but active person, his plain but intelligent countenance, was full of animation. Sir Henry Taylor tells us that he once observed Wheatstone at an evening party in Oxford earnestly holding forth to Lord Palmerston on the capabilities of his telegraph. 'You don't say so!' exclaimed the statesman. 'I must get you to tell that to the Lord Chancellor.' And so saying, he fastened the electrician on Lord Westbury, and effected his escape. A reminiscence of this interview may have prompted Palmerston to remark that a time was coming when a minister might be asked in Parliament if war had broken out in India, and would reply, 'Wait a minute; I'll just telegraph to the Governor-General, and let you know.'

Charles Wheatstone later years
Wheatstone in later years

Wheatstone was knighted in 1868, after his completion of the automatic telegraph.[2] He had previously been made a Chevalier of the Legion of Honour. Some thirty-four distinctions and diplomas of home or foreign societies bore witness to his scientific reputation. Since 1836 he had been a Fellow of the Royal Society, and in 1859 he was elected a foreign member of the Royal Swedish Academy of Sciences, and in 1873 a Foreign Associate of the French Academy of Sciences. The same year he was awarded the Ampere Medal by the French Society for the Encouragement of National Industry. In 1875, he was created an honorary member of the Institution of Civil Engineers. He was a D.C.L. of Oxford and an LL.D. of Cambridge.

While on a visit to Paris during the autumn of 1875, and engaged in perfecting his receiving instrument for submarine cables, he caught a cold, which produced inflammation of the lungs, an illness from which he died in Paris, on 19 October 1875. A memorial service was held in the Anglican Chapel, Paris, and attended by a deputation of the Academy. His remains were taken to his home in Park Crescent, London, (marked by a blue plaque today) and buried in Kensal Green Cemetery.

Music instruments and acoustics

In September 1821, Wheatstone brought himself into public notice by exhibiting the 'Enchanted Lyre,' or 'Acoucryptophone,' at a music-shop at Pall Mall and in the Adelaide Gallery. It consisted of a mimic lyre hung from the ceiling by a cord, and emitting the strains of several instruments – the piano, harp, and dulcimer. In reality it was a mere sounding box, and the cord was a steel rod that conveyed the vibrations of the music from the several instruments which were played out of sight and ear-shot. At this period Wheatstone made numerous experiments on sound and its transmission. Some of his results are preserved in Thomson's Annals of Philosophy for 1823. He recognised that sound is propagated by waves or oscillations of the atmosphere, as light was then believed to be by undulations of the luminiferous ether. Water, and solid bodies, such as glass, or metal, or sonorous wood, convey the modulations with high velocity, and he conceived the plan of transmitting sound-signals, music, or speech to long distances by this means. He estimated that sound would travel 200 miles per second (320 km/s) through solid rods, and proposed to telegraph from London to Edinburgh in this way. He even called his arrangement a 'telephone.' (Robert Hooke, in his Micrographia, published in 1667, writes: 'I can assure the reader that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light.' Nor was it essential the wire should be straight; it might be bent into angles. This property is the basis of the mechanical or lover's telephone, said to have been known to the Chinese many centuries ago. Hooke also considered the possibility of finding a way to quicken our powers of hearing.) A writer in the Repository of Arts for 1 September 1821, in referring to the 'Enchanted Lyre,' beholds the prospect of an opera being performed at the King's Theatre, and enjoyed at the Hanover Square Rooms, or even at the Horns Tavern, Kennington. The vibrations are to travel through underground conductors, like to gas in pipes.

And if music be capable of being thus conducted,' he observes, 'perhaps the words of speech may be susceptible of the same means of propagation. The eloquence of counsel, the debates of Parliament, instead of being read the next day only, – But we shall lose ourselves in the pursuit of this curious subject.

Besides transmitting sounds to a distance, Wheatstone devised a simple instrument for augmenting feeble sounds, to which he gave the name of 'Microphone.' It consisted of two slender rods, which conveyed the mechanical vibrations to both ears, and is quite different from the electrical microphone of Professor Hughes.

In 1823, his uncle, the musical instrument maker, died, and Wheatstone, with his elder brother, William, took over the business. Charles had no great liking for the commercial part, but his ingenuity found a vent in making improvements on the existing instruments, and in devising philosophical toys. He also invented instruments of his own. One of the most famous was the Wheatstone concertina. It was a six sided instrument with 64 keys. These keys provided for simple chromatic fingerings. The English Concertina became increasingly famous throughout his lifetime, however it didn't reach its peak of popularity until the early 20th century.

In 1827, Wheatstone introduced his 'kaleidophone', a device for rendering the vibrations of a sounding body apparent to the eye. It consists of a metal rod, carrying at its end a silvered bead, which reflects a 'spot' of light. As the rod vibrates the spot is seen to describe complicated figures in the air, like a spark whirled about in the darkness. His photometer was probably suggested by this appliance. It enables two lights to be compared by the relative brightness of their reflections in a silvered bead, which describes a narrow ellipse, so as to draw the spots into parallel lines.

In 1828, Wheatstone improved the German wind instrument, called the Mundharmonika, until it became the popular concertina, patented on 19 December 1829.[3] The portable harmonium is another of his inventions, which gained a prize medal at the Great Exhibition of 1851. He also improved the speaking machine of De Kempelen, and endorsed the opinion of Sir David Brewster, that before the end of this century a singing and talking apparatus would be among the conquests of science.

In 1834, Wheatstone, who had won a name for himself, was appointed to the Chair of Experimental Physics in King's College London. His first course of lectures on sound were a complete failure, due to his abhorrence of public speaking. In the rostrum he was tongue-tied and incapable, sometimes turning his back on the audience and mumbling to the diagrams on the wall. In the laboratory he felt himself at home, and ever after confined his duties mostly to demonstration.

Velocity of electricity

He achieved renown by a great experiment made in 1834 – the measurement of the velocity of electricity in a wire. He cut the wire at the middle, to form a gap which a spark might leap across, and connected its ends to the poles of a Leyden jar filled with electricity. Three sparks were thus produced, one at each end of the wire, and another at the middle. He mounted a tiny mirror on the works of a watch, so that it revolved at a high velocity, and observed the reflections of his three sparks in it. The points of the wire were so arranged that if the sparks were instantaneous, their reflections would appear in one straight line; but the middle one was seen to lag behind the others, because it was an instant later. The electricity had taken a certain time to travel from the ends of the wire to the middle. This time was found by measuring the amount of lag, and comparing it with the known velocity of the mirror. Having got the time, he had only to compare that with the length of half the wire, and he could find the velocity of electricity. His results gave a calculated velocity of 288,000 miles per second, i.e. faster than what we now know to be the speed of light (299,792.458 kilometres per second (186,000 mi/s)), but were nonetheless an interesting approximation.

It was already appreciated by some scientists that the “velocity” of electricity was dependent on the properties of the conductor and its surroundings. Francis Ronalds had observed signal retardation in his buried electric telegraph cable (but not his airborne line) in 1816 and outlined its cause to be induction.[4] Wheatstone witnessed these experiments as a youth, which were apparently a stimulus for his own research in telegraphy. Decades later, after the telegraph had been commercialised, Michael Faraday described how the velocity of an electric field in a submarine wire, coated with insulator and surrounded with water, is only 144,000 miles per second (232,000 km/s), or still less.

Wheatstone's device of the revolving mirror was afterwards employed by Léon Foucault and Hippolyte Fizeau to measure the velocity of light.

Spectroscopy

Wheatstone and others also contributed to early spectroscopy through the discovery and exploitation of spectral emission lines.[5][6][7]

As John Munro wrote in 1891, "In 1835, at the Dublin meeting of the British Association, Wheatstone showed that when metals were volatilised in the electric spark, their light, examined through a prism, revealed certain rays which were characteristic of them. Thus the kind of metals which formed the sparking points could be determined by analysing the light of the spark. This suggestion has been of great service in spectrum analysis, and as applied by Robert Bunsen, Gustav Robert Kirchhoff, and others, has led to the discovery of several new elements, such as rubidium and thallium, as well as increasing our knowledge of the heavenly bodies."[8]

Telegraph

Wheatstone abandoned his idea of transmitting intelligence by the mechanical vibration of rods, and took up the electric telegraph. In 1835 he lectured on the system of Baron Schilling, and declared that the means were already known by which an electric telegraph could be made of great service to the world. He made experiments with a plan of his own, and not only proposed to lay an experimental line across the Thames, but to establish it on the London and Birmingham Railway. Before these plans were carried out, however, he received a visit from Mr William Fothergill Cooke at his house in Conduit Street on 27 February 1837, which had an important influence on his future.

Cooperation with Cooke

Mr. Cooke was an officer in the Madras army, who, being home on leave, was attending some lectures on anatomy at the University of Heidelberg, where, on 6 March 1836, he witnessed a demonstration with the telegraph of professor Georg Wilhelm Munke, and was so impressed with its importance, that he forsook his medical studies and devoted all his efforts to the work of introducing the telegraph. He returned to London soon after, and was able to exhibit a telegraph with three needles in January 1837. Feeling his want of scientific knowledge, he consulted Michael Faraday and Peter Mark Roget (then secretary of the Royal Society), the latter of whom sent him to Wheatstone.

At a second interview, Mr. Cooke told Wheatstone of his intention to bring out a working telegraph, and explained his method. Wheatstone, according to his own statement, remarked to Cooke that the method would not act, and produced his own experimental telegraph. Finally, Cooke proposed that they should enter into a partnership, but Wheatstone was at first reluctant to comply. He was a well-known man of science, and had meant to publish his results without seeking to make capital of them. Cooke, on the other hand, declared that his sole object was to make a fortune from the scheme. In May they agreed to join their forces, Wheatstone contributing the scientific, and Cooke the administrative talent. The deed of partnership was dated 19 November 1837. A joint patent was taken out for their inventions, including the five-needle telegraph of Wheatstone,[9] and an alarm worked by a relay, in which the current, by dipping a needle into mercury, completed a local circuit, and released the detent of a clockwork.

The five-needle telegraph, which was mainly, if not entirely, due to Wheatstone, was similar to that of Schilling, and based on the principle enunciated by André-Marie Ampère – that is to say, the current was sent into the line by completing the circuit of the battery with a make and break key, and at the other end it passed through a coil of wire surrounding a magnetic needle free to turn round its centre. According as one pole of the battery or the other was applied to the line by means of the key, the current deflected the needle to one side or the other. There were five separate circuits actuating five different needles. The latter were pivoted in rows across the middle of a dial shaped like a diamond, and having the letters of the alphabet arranged upon it in such a way that a letter was literally pointed out by the current deflecting two of the needles towards it.

Early installations

GWR Cooke and Wheatstone double needle telegraph instrument
A double-needle telegraph instrument of the type used on the Great Western Railway

An experimental line, with a sixth return wire, was run between the Euston terminus and Camden Town station of the London and North Western Railway on 25 July 1837. The actual distance was only one and a half-mile (2.4 km), but spare wire had been inserted in the circuit to increase its length. It was late in the evening before the trial took place. Mr Cooke was in charge at Camden Town, while Mr Robert Stephenson and other gentlemen looked on; and Wheatstone sat at his instrument in a dingy little room, lit by a tallow candle, near the booking-office at Euston. Wheatstone sent the first message, to which Cooke replied, and 'never' said Wheatstone, 'did I feel such a tumultuous sensation before, as when, all alone in the still room, I heard the needles click, and as I spelled the words, I felt all the magnitude of the invention pronounced to be practicable beyond cavil or dispute.'

In spite of this trial, however, the directors of the railway treated the 'new-fangled' invention with indifference, and requested its removal. In July 1839, however, it was favoured by the Great Western Railway, and a line erected from the Paddington station terminus to West Drayton railway station, a distance of thirteen miles (21 km). Part of the wire was laid underground at first, but subsequently all of it was raised on posts along the line. Their circuit was eventually extended to Slough in 1841, and was publicly exhibited at Paddington as a marvel of science, which could transmit fifty signals a distance of 280,000 miles per minute (7,500 km/s). The price of admission was a shilling (£0.05), and in 1844 one fascinated observer recorded the following:

"It is perfect from the terminus of the Great Western as far as Slough – that is, eighteen miles; the wires being in some places underground in tubes, and in others high up in the air, which last, he says, is by far the best plan. We asked if the weather did not affect the wires, but he said not; a violent thunderstorm might ring a bell, but no more. We were taken into a small room (we being Mrs Drummond, Miss Philips, Harry Codrington and myself – and afterwards the Milmans and Mr Rich) where were several wooden cases containing different sorts of telegraphs. In one sort every word was spelt, and as each letter was placed in turn in a particular position, the machinery caused the electric fluid to run down the line, where it made the letter show itself at Slough, by what machinery he could not undertake to explain. After each word came a sign from Slough, signifying "I understand", coming certainly in less than one second from the end of the word......Another prints the messages it brings, so that if no-one attended to the bell,....the message would not be lost. This is effected by the electrical fluid causing a little hammer to strike the letter which presents itself, the letter which is raised hits some manifold writing paper (a new invention, black paper which, if pressed, leaves an indelible black mark), by which means the impression is left on white paper beneath. This was the most ingenious of all, and apparently Mr. Wheatstone's favourite; he was very good-natured in explaining but understands it so well himself that he cannot feel how little we know about it, and goes too fast for such ignorant folk to follow him in everything. Mrs Drummond told me he is wonderful for the rapidity with which he thinks and his power of invention; he invents so many things that he cannot put half his ideas into execution, but leaves them to be picked up and used by others, who get the credit of them."[10]

Public attention and success

The public took to the new invention after the capture of the murderer John Tawell, who in 1845, had become the first person to be arrested as the result of telecommunications technology. In the same year, Wheatstone introduced two improved forms of the apparatus, namely, the 'single' and the 'double' needle instruments, in which the signals were made by the successive deflections of the needles. Of these, the single-needle instrument, requiring only one wire, is still in use.

The development of the telegraph may be gathered from two facts. In 1855, the death of the Emperor Nicholas at St. Petersburg, about one o'clock in the afternoon, was announced in the House of Lords a few hours later. The result of The Oaks of 1890 was received in New York fifteen seconds after the horses passed the winning-post.

Differences with Cooke

In 1841 a difference arose between Cooke and Wheatstone as to the share of each in the honour of inventing the telegraph. The question was submitted to the arbitration of the famous engineer, Marc Isambard Brunel, on behalf of Cooke, and Professor Daniell, of King's College, the inventor of the Daniell battery, on the part of Wheatstone. They awarded to Cooke the credit of having introduced the telegraph as a useful undertaking which promised to be of national importance, and to Wheatstone that of having by his researches prepared the public to receive it. They concluded with the words: 'It is to the united labours of two gentlemen so well qualified for mutual assistance that we must attribute the rapid progress which this important invention has made during five years since they have been associated.' The decision, however vague, pronounces the needle telegraph a joint production. If it had mainly been invented by Wheatstone, it was chiefly introduced by Cooke. Their respective shares in the undertaking might be compared to that of an author and his publisher, but for the fact that Cooke himself had a share in the actual work of invention.

Further work on telegraphs

From 1836–7 Wheatstone had thought a good deal about submarine telegraphs, and in 1840 he gave evidence before the Railway Committee of the House of Commons on the feasibility of the proposed line from Dover to Calais. He had even designed the machinery for making and laying the cable. In the autumn of 1844, with the assistance of Mr. J. D. Llewellyn, he submerged a length of insulated wire in Swansea Bay, and signalled through it from a boat to the Mumbles Lighthouse. Next year he suggested the use of gutta-percha for the coating of the intended wire across the English Channel.

In 1840 Wheatstone had patented an alphabetical telegraph, or, 'Wheatstone A B C instrument,' which moved with a step-by-step motion, and showed the letters of the message upon a dial. The same principle was used in his type-printing telegraph, patented in 1841. This was the first apparatus which printed a telegram in type. It was worked by two circuits, and as the type revolved a hammer, actuated by the current, pressed the required letter on the paper.

The introduction of the telegraph had so far advanced that, on 2 September 1845, the Electric Telegraph Company was registered, and Wheatstone, by his deed of partnership with Cooke, received a sum of £33,000 for the use of their joint inventions.

In 1859 Wheatstone was appointed by the Board of Trade to report on the subject of the Atlantic cables, and in 1864 he was one of the experts who advised the Atlantic Telegraph Company on the construction of the successful lines of 1865 and 1866.

In 1870 the electric telegraph lines of the United Kingdom, worked by different companies, were transferred to the Post Office, and placed under Government control.

Wheatstone further invented the automatic transmitter, in which the signals of the message are first punched out on a strip of paper, which is then passed through the sending-key, and controls the signal currents. By substituting a mechanism for the hand in sending the message, he was able to telegraph about 100 words a minute, or five times the ordinary rate. In the Postal Telegraph service this apparatus is employed for sending Press telegrams, and it has recently been so much improved, that messages are now sent from London to Bristol at a speed of 600 words a minute, and even of 400 words a minute between London and Aberdeen. On the night of 8 April 1886, when Mr. Gladstone introduced his Bill for Home Rule in Ireland, no fewer than 1,500,000 words were dispatched from the central station at St. Martin's-le-Grand by 100 Wheatstone transmitters. The plan of sending messages by a running strip of paper which actuates the key was originally patented by Bain in 1846; but Wheatstone, aided by Mr. Augustus Stroh, an accomplished mechanician, and an able experimenter, was the first to bring the idea into successful operation. This system is often referred to as the Wheatstone Perforator[11] and is the forerunner of the stock market Ticker tape[12]

Optics

Charles Wheatstone-mirror stereoscope XIXc
Charles Wheatstone mirror stereoscope

Stereopsis was first described by Wheatstone in 1838.[13] In 1840 he was awarded the Royal Medal of the Royal Society for his explanation of binocular vision, a research which led him to make stereoscopic drawings and construct the stereoscope. He showed that our impression of solidity is gained by the combination in the mind of two separate pictures of an object taken by both of our eyes from different points of view. Thus, in the stereoscope, an arrangement of lenses or mirrors, two photographs of the same object taken from different points are so combined as to make the object stand out with a solid aspect. Sir David Brewster improved the stereoscope by dispensing with the mirrors, and bringing it into its existing form with lenses.

The 'pseudoscope' (Wheatstone coined the term from the Greek ψευδίς σκοπειν) was introduced in 1852,[14] and is in some sort the reverse of the stereoscope, since it causes a solid object to seem hollow, and a nearer one to be farther off; thus, a bust appears to be a mask, and a tree growing outside of a window looks as if it were growing inside the room. Its purpose was to test his theory of stereo vision and for investigations into what would now be called experimental psychology.

Measuring time

In 1840, Wheatstone introduced his chronoscope, for measuring minute intervals of time, which was used in determining the speed of a bullet or the passage of a star. In this apparatus an electric current actuated an electro-magnet, which noted the instant of an occurrence by means of a pencil on a moving paper. It is said to have been capable of distinguishing 1/7300 part of a second (137 microsecond), and the time a body took to fall from a height of one inch (25 mm).

On 26 November 1840, he exhibited his electro-magnetic clock in the library of the Royal Society, and propounded a plan for distributing the correct time from a standard clock to a number of local timepieces. The circuits of these were to be electrified by a key or contact-maker actuated by the arbour of the standard, and their hands corrected by electro-magnetism. The following January Alexander Bain took out a patent for an electro-magnetic clock, and he subsequently charged Wheatstone with appropriating his ideas. It appears that Bain worked as a mechanist to Wheatstone from August to December 1840, and he asserted that he had communicated the idea of an electric clock to Wheatstone during that period; but Wheatstone maintained that he had experimented in that direction during May. Bain further accused Wheatstone of stealing his idea of the electro-magnetic printing telegraph; but Wheatstone showed that the instrument was only a modification of his own electro-magnetic telegraph.

In 1840, Alexander Bain mentioned to the Mechanics Magazine editor his financial problems. He introduced him to Sir Charles Wheatstone. Bain demonstrated his models to Wheatstone, who, when asked for his opinion, said "Oh, I shouldn't bother to develop these things any further! There's no future in them."[2] Three months later Wheatstone demonstrated an electric clock to the Royal Society, claiming it was his own invention. However, Bain had already applied for a patent for it. Wheatstone tried to block Bain's patents, but failed. When Wheatstone organised an Act of Parliament to set up the Electric Telegraph Company, the House of Lords summoned Bain to give evidence, and eventually compelled the company to pay Bain £10,000 and give him a job as manager, causing Wheatstone to resign.

Polar clock

One of Wheatstone's most ingenious devices was the 'Polar clock,' exhibited at the meeting of the British Association in 1848. It is based on the fact discovered by Sir David Brewster, that the light of the sky is polarised in a plane at an angle of ninety degrees from the position of the sun. It follows that by discovering that plane of polarisation, and measuring its azimuth with respect to the north, the position of the sun, although beneath the horizon, could be determined, and the apparent solar time obtained. The clock consisted of a spyglass, having a Nicol (double-image) prism for an eyepiece, and a thin plate of selenite for an object-glass. When the tube was directed to the North Pole—that is, parallel to the Earth's axis—and the prism of the eyepiece turned until no colour was seen, the angle of turning, as shown by an index moving with the prism over a graduated limb, gave the hour of day. The device is of little service in a country where watches are reliable; but it formed part of the equipment of the 1875–1876 North Polar expedition commanded by Captain Nares.

Wheatstone bridge

In 1843 Wheatstone communicated an important paper to the Royal Society, entitled 'An Account of Several New Processes for Determining the Constants of a Voltaic Circuit.' It contained an exposition of the well known balance for measuring the electrical resistance of a conductor, which still goes by the name of Wheatstone's Bridge or balance, although it was first devised by Samuel Hunter Christie, of the Royal Military Academy, Woolwich, who published it in the Philosophical Transactions for 1833. The method was neglected until Wheatstone brought it into notice. His paper abounds with simple and practical formulae for the calculation of currents and resistances by the law of Ohm. He introduced a unit of resistance, namely, a foot of copper wire weighing one hundred grains (6.5 g), and showed how it might be applied to measure the length of wire by its resistance. He was awarded a medal for his paper by the Society.[15] The same year he invented an apparatus which enabled the reading of a thermometer or a barometer to be registered at a distance by means of an electric contact made by the mercury. A sound telegraph, in which the signals were given by the strokes of a bell, was also patented by Cooke and Wheatstone in May of that year.

Cryptography

Wheatstone's remarkable ingenuity was also displayed in the invention of cyphers. He was responsible for the then unusual Playfair cipher, named after his friend Lord Playfair. It was used by the militaries of several nations through at least World War I, and is known to have been used during World War II by British intelligence services.[16]

It was initially resistant to cryptanalysis, but methods were eventually developed to break it. He also became involved in the interpretation of cypher manuscripts in the British Museum. He devised a cryptograph or machine for turning a message into cypher which could only be interpreted by putting the cypher into a corresponding machine adjusted to decrypt it.

Electrical generators

In 1840, Wheatstone brought out his magneto-electric machine for generating continuous currents.

On 4 February 1867, he published the principle of reaction in the dynamo-electric machine by a paper to the Royal Society; but Mr. C. W. Siemens had communicated the identical discovery ten days earlier, and both papers were read on the same day.

It afterwards appeared that Werner von Siemens, Samuel Alfred Varley, and Wheatstone had independently arrived at the principle within a few months of each other. Varley patented it on 24 December 1866; Siemens called attention to it on 17 January 1867; and Wheatstone exhibited it in action at the Royal Society on the above date.

Disputes over invention

Wheatstone was involved in various disputes with other scientists throughout his life regarding his role in different technologies and appeared at times to take more credit than he was due. As well as William Fothergill Cooke, Alexander Bain and David Brewster, mentioned above, these also included Francis Ronalds at the Kew Observatory. Wheatstone was erroneously believed by many to have created the atmospheric electricity observing apparatus that Ronalds invented and developed at the observatory in the 1840s and also to have installed the first automatic recording meteorological instruments there (see for example, Howarth, p158).[17][18]

See also

References

  1. ^ "Wheatstone, Sir Charles". Oxford Dictionaries. Retrieved 28 January 2015.
  2. ^ "No. 23349". The London Gazette. 4 February 1868. p. 535.
  3. ^ Gaskins, Robert. "Portfolio of Historic Concertina Patents". www.concertina.com. Retrieved 19 March 2018.
  4. ^ Ronalds, B.F. (2016). "Sir Francis Ronalds and the Electric Telegraph". Int. J. for the History of Engineering & Technology. doi:10.1080/17581206.2015.1119481.
  5. ^ Brian Bowers (2001). Sir Charles Wheatstone FRS: 1802–1875 (2nd ed.). IET. pp. 207–208. ISBN 978-0-85296-103-2.
  6. ^ George Gore (1878). The Art of Scientific Discovery: Or, The General Conditions and Methods of Research in Physics and Chemistry. Longmans, Green, and Co. p. 179.
  7. ^ Wheatstone (1836). "On the prismatic decomposition of electrical light". Report of the Fifth Meeting of the British Association for the Advancement of Science; Held at Dublin in 1835. Notices and Abstracts of Communications to the British Association for the Advancement of Science, at the Dublin Meeting, August 1835. London, England: John Murray. pp. 11–12.
  8. ^ John Munro (1891). Heroes of the telegraph. The Religious tract society. p. 30.
  9. ^ Beauchamp, Ken (2001). History of Telegraphy. Institution of Electrical Engineers. pp. 34–40.
  10. ^ Sullivan, Gertrude : A Family Chronicle published in 1908 (London, John Murray) by her niece, Gertrude Lyster. Pages 216–7.
  11. ^ Bemer, Bob. "How ASCII Got Its Backslash". Retrieved 4 August 2014.
  12. ^ "Kleinschmidt – Our History". Archived from the original on 22 April 2014. Retrieved 4 August 2014.
  13. ^ See Wheatstone's 1838 paper "Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision" at this site.
  14. ^ See Wheatstone's 1852 Bakerian Lecture "Contributions to the Physiology of Vision. – Part the Second. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision (continued)" at this site.
  15. ^ "The Genesis of the Wheatstone Bridge" by Stig Ekelof discusses Christie's and Wheatstone's contributions, and why the bridge carries Wheatstone's name. Published in "Engineering Science and Education Journal", volume 10, no 1, February 2001, pages 37 – 40.
  16. ^ Marks, Leo (1998). Between Silk and Cyanide. New York: The Free Press. ISBN 0-684-86422-3.
  17. ^ Ronalds, B.F. (2016). Sir Francis Ronalds: Father of the Electric Telegraph. London: Imperial College Press. ISBN 978-1-78326-917-4.
  18. ^ Howarth, O.J. (1922). The British Association for the Advancement of Science: A retrospect 1831–1921.

Further reading

External links

Annals of Philosophy

Annals of Philosophy was a learned journal founded in 1813 by the Scottish chemist Thomas Thomson. It shortly became a leader in its field of commercial scientific periodicals. Contributors included John George Children, Edward Daniel Clarke, Philip Crampton, Alexander Crichton, James Cumming, John Herapath, William George Horner, Thomas Dick Lauder, John Miers, Matthew Paul Moyle, Robert Porrett, James Thomson, and Charles Wheatstone.Thomson edited it until 1821, when he was succeeded in 1821 by Richard Phillips. The journal was bought by Richard Taylor in 1827, and closed down for the benefit of the Philosophical Magazine.The Annals of Philosophy were issued monthly following a standard pattern. Often the first article was a biographical article (10 pages) on a living or recently deceased scientist. This was then followed by a series of extended pieces (5-10 pages) on particular topics, sometimes by eminent authors. Then there were shorter news items and correspondence. Summaries followed: first of the proceedings of learned bodies (Royal Society, Linnean, French Institute -if available: the Napoleonic Wars made communications with the continent difficult at first, etc.), then of patents, and finally of new books. The last section was a meteorological journal. Every six months a title page, index, and preface were issued which could be bound before the six monthly issues to make a half-yearly volume. Including front matter, volumes were just under 500 pages each.

Barnwood

Barnwood, in Gloucestershire, England is on the old Roman road that links the City of Gloucester with Hucclecote, Brockworth and Cirencester.

Barnwood was originally a small village. The Church of England parish church of St Lawrence, about two miles east of the city centre of Gloucester, is known for The Barnwood Guild of Church Bellringers, inaugurated in 1952. However, bell ringing has a long history in the Gloucester area and Barnwood had long been a part of it when its activities were disrupted by World War II.

Samuel and Anne Bubb, who were grandparents of the inventor Sir Charles Wheatstone (1802–75), lived at Barnwood Manor House. Biographical notes of 1887 say that Sir Charles stated that he was born in the house and lived there as a young child, and this was the scene of some of his earliest experiments. In later years Wheatstone often returned to Barnwood. A local public house is named The Wheatstone Inn after him.

The architect Frederick S. Waller (1822–1905), sometime resident architect at Gloucester Cathedral, lived and died at Barnwood.The Generation Design and Construction Division of the CEGB became the centre of a new office development when it moved here in the early 1970s. This then became the corporate headquarters of Nuclear Electric, and later the English offices of the (nominally Scottish-based) British Energy, which in 2009 became part of EDF Energy. Other major companies in Barnwood include Claranet, Cheltenham & Gloucester and InterCall. There is also a Holiday Inn, Sainsbury's, Virgin Active and Tenpin Ltd in the area.

Barnwood Park Arts College is a girls' secondary school located in the area.

Brewster Island

Brewster Island (64°43′S 62°34′W) is a small island lying northeast of Danco Island in Errera Channel, off the west coast of Graham Land. It was shown on an Argentine government chart of 1950, and named by the UK Antarctic Place-Names Committee in 1960 for Sir David Brewster, Scottish natural philosopher who in 1844 improved the mirror stereoscope invented by Sir Charles Wheatstone by substituting prisms.

Bridge circuit

A bridge circuit is a topology of electrical circuitry in which two circuit branches (usually in parallel with each other) are "bridged" by a third branch connected between the first two branches at some intermediate point along them. The bridge was originally developed for laboratory measurement purposes and one of the intermediate bridging points is often adjustable when so used. Bridge circuits now find many applications, both linear and non-linear, including in instrumentation, filtering and power conversion.

The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance. It is constructed from four resistors, two of known values R1 and R3 (see diagram), one whose resistance is to be determined Rx, and one which is variable and calibrated R2. Two opposite vertices are connected to a source of electric current, such as a battery, and a galvanometer is connected across the other two vertices. The variable resistor is adjusted until the galvanometer reads zero. It is then known that the ratio between the variable resistor and its neighbour R1 is equal to the ratio between the unknown resistor and its neighbour R3, which enables the value of the unknown resistor to be calculated.

The Wheatstone bridge has also been generalised to measure impedance in AC circuits, and to measure resistance, inductance, capacitance, and dissipation factor separately. Variants are known as the Wien bridge, Maxwell bridge, and Heaviside bridge (used to measure the effect of mutual inductance). All are based on the same principle, which is to compare the output of two potential dividers sharing a common source.

In power supply design, a bridge circuit or bridge rectifier is an arrangement of diodes or similar devices used to rectify an electric current, i.e. to convert it from an unknown or alternating polarity to a direct current of known polarity.

In some motor controllers, an H-bridge is used to control the direction the motor turns.

Carl Friedrich Uhlig

Carl Friedrich Uhlig (1789–1874) was a German luthier, known for inventing the German family of concertinas, from which are descended variants such as the bandoneón, Carlsfelder concertina, and Chemnitzer concertina.

Uhlig produced his first concertina in 1834, being dissatisfied with the early accordion keyboard developed by Cyrill Demian. Uhlig took the right-handed keyboard of Demian, and split it between the two hands, resulting in an instrument which had two separate keyboards producing individual notes. While Uhlig's development of the concertina is very parallel to that of Charles Wheatstone, the founder of the English family of concertinas, there is no definite indication they were aware of each other's work.

Concertina

A concertina is a free-reed musical instrument, like the various accordions and the harmonica. It consists of expanding and contracting bellows, with buttons (or keys) usually on both ends, unlike accordion buttons, which are on the front.

The concertina was developed in England and Germany. The English version was invented in 1829 by Sir Charles Wheatstone, while Carl Friedrich Uhlig announced the German version five years later, in 1834. Various forms of concertina are used for classical music, for the traditional musics of Ireland, England, and South Africa, and for tango and polka music.

Cooke and Wheatstone telegraph

The Cooke and Wheatstone telegraph was an early electrical telegraph system dating from the 1830s invented by English inventor William Fothergill Cooke and English scientist Charles Wheatstone. It was a form of needle telegraph, and the first telegraph system to be put into commercial service. The receiver consisted of a number of needles which could be moved by electromagnetic coils to point to letters on a board. This feature was liked by early users who were unwilling to learn codes, and employers who did not want to invest in staff training.

In later systems the letter board was dispensed with, and the code was read directly from the movement of the needles. This came about because the number of needles was reduced, leading to more complex codes. The change was motivated by the economic need to reduce the number of telegraph wires used, which was related to the number of needles. The change became more urgent as the insulation of some of the early installations deteriorated, causing some of the original wires to be unusable. Cooke and Wheatstone's most successful system was eventually a one-needle system that continued in service into the 1930s.

Cooke and Wheatstone's telegraph played a part in the apprehension of the murderer John Tawell. Once it was known that Tawell had boarded a train to London, the telegraph was used to signal ahead to the terminus at Paddington and have him arrested there. The novelty of this use of the telegraph in crime-fighting generated a great deal of publicity and led to increased acceptance and use of the telegraph by the public.

Electric Telegraph Company

The Electric Telegraph Company (ETC) was a British telegraph company founded in 1846 by William Fothergill Cooke and John Ricardo. It was the world's first public telegraph company. The equipment used was the Cooke and Wheatstone telegraph, an electrical telegraph developed a few years earlier in collaboration with Charles Wheatstone. The system had been taken up by several railway companies for signalling purposes, but in forming the company Cooke intended to open up the technology to the public at large.

The ETC had a monopoly of electrical telegraphy until the formation of the Magnetic Telegraph Company (commonly called the Magnetic) who used a different system which did not infringe the ETC's patents. The Magnetic became the chief rival of the ETC and the two of them dominated the market even after further companies entered the field.

The ETC was heavily involved in laying submarine telegraph cables, including lines to the Netherlands, Ireland, the Channel Islands, and the Isle of Man. It operated the world's first specialised cable-laying ship, the Monarch. A private line was laid for Queen Victoria on the Isle of Wight. The company was nationalised in 1870 along with other British telegraph companies, and its assets were taken over by the General Post Office.

King George III Museum

The King George III Museum was a museum within King's College London, England between 1843 and 1927 which held the collections of scientific instruments of George III as well as eminent nineteenth-century scientists including Sir Charles Wheatstone and Charles Babbage. The collection of scientific and mathematical instruments assembled by George III, after whom the museum is named, was donated to the university by Queen Victoria in 1841, and the museum was opened by Albert, Prince Consort on 1 July 1843. The museum was located within the King's Building designed by Sir Robert Smirke. It counted among its collections the unfinished prototype of the Difference Engine No. 1, designed by Charles Babbage, who is considered a "father of the computer". The museum closed in 1926, and much of its collections were transferred on loan to the Science Museum, London.

Ludimar Hermann

Ludimar Hermann (October 31, 1838, Berlin – June 5, 1914, Königsberg) was a German physiologist and speech scientist who used the Edison phonograph to test theories of vowel production, particularly those of Robert Willis and Charles Wheatstone. He coined the word formant, a term of importance in modern acoustic phonetics. The Hermann Grid is named after him; he was the first to report the illusion in scientific literature.

Needle telegraph

A needle telegraph is an electrical telegraph that uses indicating needles moved electromagnetically as its means of displaying messages. It is one of the two main types of electromagnetic telegraph, the other being the armature system as exemplified by the telegraph of Samuel Morse in the United States. The principal needle system was the Cooke and Wheatstone telegraph, a system widely used in Britain and the British Empire in the 19th and early-20th centuries. However, the earliest needle telegraph was a binary coded multi-wire, multi-needle system invented by Pavel Schilling and demonstrated in St. Petersburg in 1832. Charles Wheatstone may have demonstrated one of Schilling's instruments in 1835 (that is, prior to his collaboration with Cooke to build a telegraph). Cooke definitely saw Schilling's needle instrument at a lecture of Georg Wilhelm Muncke in Heidelberg. It was this lecture that inspired Cooke to attempt building a telegraph, although he did not use needle instruments until Wheatstone came on board and suggested it.Other examples include;

Foy-Breguet telegraph, invented by Alphonse Foy and Louis-François-Clement Breguet in 1842, and used in France

Henley-Foster telegraph, invented in 1848 by William Thomas Henley and George Foster, and used by the British and Irish Magnetic Telegraph Company. This system did not require batteries.

Playfair cipher

The Playfair cipher or Playfair square or Wheatstone-Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use.

The technique encrypts pairs of letters (bigrams or digrams), instead of single letters as in the simple substitution cipher and rather more complex Vigenère cipher systems then in use. The Playfair is thus significantly harder to break since the frequency analysis used for simple substitution ciphers does not work with it. The frequency analysis of bigrams is possible, but considerably more difficult. With 600 possible bigrams rather than the 26 possible monograms (single symbols, usually letters in this context), a considerably larger cipher text is required in order to be useful.

Pseudoscope

A pseudoscope is a binocular optical instrument that reverses depth perception. It is used to study human stereoscopic perception. Objects viewed through it appear inside out, for example: a box on a floor would appear as a box shaped hole in the floor.

It typically uses sets of optical prisms, or periscopically arranged mirrors to swap the view of the left eye with that of the right eye.

Universal Private Telegraph Company

The Universal Private Telegraph Company, Limited was formed in 1861 to exploit Professor Charles Wheatstone’s 1858 Universal Telegraph. The company was to "...carry out a system by which banks, merchants, public bodies and other parties may have the means of establishing a telegraph for their own private purposes from their houses to their offices, manufactories or other places".The company's first directors were Charles Wheatstone and William Fairbairn, CE, the Manchester ironmaster. It employed Thomas Page, engineer, Lewis Hertslet, secretary and Nathaniel Holmes, electrician.

Wadsworth's cipher

Wadsworth's cipher, or Wheatstone's cipher, was a cipher invented by Decius Wadsworth, a Colonel in the Ordnance Corps of the United States Army. In 1817, he developed a progressive cipher system based on a 1790 design by Thomas Jefferson, establishing a method that was continuously improved upon and used until the end of World War II.

Wadsworth's system involved a set of two disks, one inside the other, where the outer disk had the 26 letters of the alphabet and the numbers 2-8, and the inner disk had only the 26 letters. The disks were geared together at a ratio of 26:33. To encipher a message, the inner disk was turned until the desired letter was at the top position, with the number of turns required for the result transmitted as ciphertext. Due to the gearing, a ciphertext substitution for a character did not repeat until all 33 characters for the plaintext letter had been used. Wadsworth never got credit for his design because Charles Wheatstone invented an almost identical machine several years after Wadsworth, and got all the credit.

Wheatstone

Wheatstone may refer to:

Cape Wheatstone, in Antarctica

Charles Wheatstone (1802–1875), a British scientist and inventor, eponymous for Wheatstone bridge

Cooke and Wheatstone Telegraph

Wheatstone, New Zealand, a locality in the Canterbury region

Wheatstone Glacier, in Antarctica

Wheatstone LNG

Wheatstone bridge, a measuring instrument in electricity

Wheatstone Corporation, an American manufacturing company

Wheatstone bridge

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements (in contrast with something like a simple voltage divider). Its operation is similar to the original potentiometer.

The Wheatstone bridge was invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843. One of the Wheatstone bridge's initial uses was for the purpose of soils analysis and comparison.

William Fothergill Cooke

Sir William Fothergill Cooke (4 May 1806 – 25 June 1879) was an English inventor. He was, with Charles Wheatstone, the co-inventor of the Cooke-Wheatstone electrical telegraph, which was patented in May 1837. Together with John Lewis Ricardo he founded the Electric Telegraph Company, the world's first public telegraph company, in 1846. He was knighted in 1869.

Willoughby Smith

Willoughby Smith (6 April 1828, Great Yarmouth, Norfolk – 17 July 1891, Eastbourne, Sussex) was an English electrical engineer who discovered the photoconductivity of the element selenium. This discovery led to the invention of photoelectric cells, including those used in the earliest television systems.

In 1848, he began working for the Gutta Percha Company, London where he developed iron and copper wires insulated with gutta-percha to be used for telegraph wires. In 1849, Smith superintended the manufacture and laying of 30 miles of underwater telegraph wire from Dover to Calais. He worked closely with Charles Wheatstone who had designed the machinery for making and laying the cable.

The project was a success and over the following decades, Smith and the company he worked for were involved with many other underwater telegraph cable projects.

In 1873, Smith developed a method for continually testing an underwater cable as it was being laid. For his test circuit, he needed a semi-conducting material with a high resistance and selected selenium rods for this purpose.

The selenium seemed to do the job properly, except in actual use, the device gave inconsistent results. Upon investigation, it was discovered that the conductivity of the selenium rods increased significantly when exposed to strong light.

Smith described the "Effect of Light on Selenium during the passage of an Electric Current" in an article that was published in the 20 February 1873 issue of Nature.

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